1. Field of the Invention
The present system relates to devices used in the drilling of wells, and more particularly, to a wellbore anchoring system for use with wellbore tools such as whipstocks.
2. Description of the Related Art
Wellbore anchoring systems may be used to anchor drilling equipment downhole, or to permit certain wellbore operations. Some anchoring systems may be used, for example, to fix inclined planes or wedges in the bore, such as a whipstock, for deflecting or changing the angle or direction of drilling from that of the original borehole.
Some approaches use an inflatable element within the anchoring system for open holes. The inflatable packer element expands during inflation to grip the formation about the wellbore. Inflatable elements may be limited in gripping ability, particularly if subjected to an axial force. However, if the inflation media permits deflation, then the anchor system may be withdrawn after use.
Approaches using mechanical anchors typically have either dogs that mate with channels installed within the wellbore, or members that may be forced into a lateral position relative to the borehole, such as teeth or slips that bite into the sides of a wellbore when expanded (or ‘set.’)
In many cases, the anchoring systems rely on mechanical devices for setting the slips into position while in position downhole. Such approaches can be complicated by distance and the considerable forces required, which in some cases reduces the grip or security of the anchor. For example, some anchoring systems require a separate setting tool to apply the setting force to the anchor system via a mandrel. Such a tool might activate a slip cone, for example, so that it moves within the anchor; the increasing cross section of the cone may then force the slips to expand. Apart from added expense and complexity, a setting tool must be able to apply a sufficient setting force to the anchor system while both the anchor and the tool are at the desired location down hole.
Some conventional approaches involve devices that are not capable of removal once set. Other conventional approaches may be removable, but require substantial upward forces to be applied to a set anchoring system. A need exists for an anchor system with improved reliability, simplicity, and lower removal forces over conventionally available anchor devices.